Detection of bias in animal model pedigree indices of heifers
The objective of the study was to test whether the pedigree indices (PI) of heifers are biased, and if so, whether the magnitude of the bias varies in different groups of heifers. Therefore, two animal model evaluations with two different data sets were computed. Data with all the records from the n...
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| Format: | Article |
| Language: | English |
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Scientific Agricultural Society of Finland
2008-12-01
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| Series: | Agricultural and Food Science |
| Online Access: | https://journal.fi/afs/article/view/5528 |
| _version_ | 1811283603311558656 |
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| author | M. LIDAUER E. MÄNTYSAARI |
| author_facet | M. LIDAUER E. MÄNTYSAARI |
| author_sort | M. LIDAUER |
| collection | DOAJ |
| description | The objective of the study was to test whether the pedigree indices (PI) of heifers are biased, and if so, whether the magnitude of the bias varies in different groups of heifers. Therefore, two animal model evaluations with two different data sets were computed. Data with all the records from the national evaluation in December 1994 was used to obtain estimated breeding values (EBV) for 305-days' milk yield and protein yield. In the second evaluation, the PIs were estimated for cows calving the first time in 1993 by excluding all their production records from the data. Three different statistics, a simple t-test, the linear regression of EBV on PI, and the polynomial regression of the difference in the predictions (EBV-PI) on PI, were computed for three groups of first parity Ayrshire cows: daughters of proven sires, daughters of young sires, and daughters of bull dam candidates. A practically relevant bias was found only in the PIs for the daughters of young sires. On average their PIs were biased upwards by 0.20 standard deviations (78.8 kg) for the milk yield and by 0.21 standard deviations (2.2 kg) for the protein yield. The polynomial regression analysis showed that the magnitude of the bias in the PIs changed somewhat with the size of the PIs.; |
| first_indexed | 2024-04-13T02:14:32Z |
| format | Article |
| id | doaj.art-178c7adfa3c04bdaa7e9740985ef3968 |
| institution | Directory Open Access Journal |
| issn | 1459-6067 1795-1895 |
| language | English |
| last_indexed | 2024-04-13T02:14:32Z |
| publishDate | 2008-12-01 |
| publisher | Scientific Agricultural Society of Finland |
| record_format | Article |
| series | Agricultural and Food Science |
| spelling | doaj.art-178c7adfa3c04bdaa7e9740985ef39682022-12-22T03:07:11ZengScientific Agricultural Society of FinlandAgricultural and Food Science1459-60671795-18952008-12-0154Detection of bias in animal model pedigree indices of heifersM. LIDAUERE. MÄNTYSAARIThe objective of the study was to test whether the pedigree indices (PI) of heifers are biased, and if so, whether the magnitude of the bias varies in different groups of heifers. Therefore, two animal model evaluations with two different data sets were computed. Data with all the records from the national evaluation in December 1994 was used to obtain estimated breeding values (EBV) for 305-days' milk yield and protein yield. In the second evaluation, the PIs were estimated for cows calving the first time in 1993 by excluding all their production records from the data. Three different statistics, a simple t-test, the linear regression of EBV on PI, and the polynomial regression of the difference in the predictions (EBV-PI) on PI, were computed for three groups of first parity Ayrshire cows: daughters of proven sires, daughters of young sires, and daughters of bull dam candidates. A practically relevant bias was found only in the PIs for the daughters of young sires. On average their PIs were biased upwards by 0.20 standard deviations (78.8 kg) for the milk yield and by 0.21 standard deviations (2.2 kg) for the protein yield. The polynomial regression analysis showed that the magnitude of the bias in the PIs changed somewhat with the size of the PIs.;https://journal.fi/afs/article/view/5528 |
| spellingShingle | M. LIDAUER E. MÄNTYSAARI Detection of bias in animal model pedigree indices of heifers Agricultural and Food Science |
| title | Detection of bias in animal model pedigree indices of heifers |
| title_full | Detection of bias in animal model pedigree indices of heifers |
| title_fullStr | Detection of bias in animal model pedigree indices of heifers |
| title_full_unstemmed | Detection of bias in animal model pedigree indices of heifers |
| title_short | Detection of bias in animal model pedigree indices of heifers |
| title_sort | detection of bias in animal model pedigree indices of heifers |
| url | https://journal.fi/afs/article/view/5528 |
| work_keys_str_mv | AT mlidauer detectionofbiasinanimalmodelpedigreeindicesofheifers AT emantysaari detectionofbiasinanimalmodelpedigreeindicesofheifers |